Inara Consultancy Services React Js Software Engineer Interview Questions and Answers

Virtual DOM is a lightweight copy of the actual DOM that React uses to improve performance by minimizing direct manipulation of the actual DOM.

• Virtual DOM is a concept in React where a lightweight copy of the actual DOM is created and updated in memory.

• When changes are made to the virtual DOM, React compares it with the actual DOM and only updates the necessary parts, reducing the number of direct manipulations to the ...read more

useEffect is a hook in React that allows performing side effects in function components.

• useEffect is used to perform side effects in function components.

• It runs after every render by default.

• It can be used to fetch data, subscribe to events, or update the DOM.

• It can also clean up effects from previous renders.

• It takes two arguments: a function and an optional array of dependencies.

Create a stopwatch in React using state and lifecycle methods.

• Use state to store the current time and whether the stopwatch is running.

• Use lifecycle methods like componentDidMount and componentWillUnmount to start and stop the stopwatch.

• Use setInterval to update the time every second.

• Display the time in a user-friendly format like HH:MM:SS.